1. Technical Field
The present disclosure relates to a control device and a control method for an internal combustion engine.
2. Description of the Related Art
A control device for an internal combustion engine that performs a lean burn operation with a larger lean air-fuel ratio than a stoichiometric air-fuel ratio is disclosed in Japanese Patent Application Publication No. 10-176570 (JP 10-176570 A). In this control device, the retardation amount of ignition timing is calculated on the basis of a result of detecting knocking by a knocking sensor, and a torque fluctuation value is calculated using an output value of a crank angle sensor. Then, in a case where the calculated torque fluctuation value exceeds a target value, an increase in the amount of injected fuel is executed for enrichment of the air-fuel ratio. Additionally, in a case where the retardation amount of the ignition timing exceeds a predetermined amount, the execution of the increase in the amount of injected fuel is limited.
The control device for the internal combustion engine may perform retardation of the ignition timing for purposes, such as knocking suppression, according to a retardation request for the ignition timing. Torque fluctuation becomes large if the ignition timing is retarded. According to JP 10-176570 A, in order to perform the enrichment of the air-fuel ratio for suppressing the torque fluctuation, it is required to actually calculate the torque fluctuation value.